Canva

Someone can help me about canva tool?

I assume you mean the canvas (with an "s") tool. Is that right? I do not use this tool, but it might be good to get some clarification. 

How can I get the last canva?

Do you mean, "how can I open the last canvas project?" You open it in the "docs" menu. 

Or how can I save it before close the window?

I think you need to name it.